Minimum 10-year outcomes of a fixed bearing all-polyethylene unicompartmental knee arthroplasty used to treat medial osteoarthritis.

BACKGROUND: Unicompartmental knee arthroplasty (UKA) accounts for 8.9% of knee arthroplasty procedures in England, Wales and Northern Ireland. Fixed bearing UKA designs have shown favourable survivorship in registries when compared with mobile bearings but some studies suggest poor survival of all-polyethylene fixed tibial bearings. This study analyses long-term follow-up of patients with a medial fixed all-polyethylene tibial bearing UKA and reports survivorship and 10-year clinical outcomes. METHODS: Data was collected prospectively for 214 medial unicompartmental all-polyethylene tibial bearing UKAs implanted in 184 patients at our tertiary referral centre between November 2002 and December 2007. The indication was osteoarthritis in all but one patient. Patient reported outcome scores were documented pre-operatively and at five, eight, 10 and 12 years of follow-up. The mean patient age was 70 years (range 41-87). RESULTS: Outcome and survivorship data were collected for 214 medial all-polyethylene tibial bearing UKAs. There were outcomes recorded for 83 UKAs with at least 10-year follow-up. Twenty-four patients underwent revision of their UKA at an average of 5.84 years after the primary procedure. Kaplan-Meier analysis demonstrated survivorship of 89.1% at 10 years and the OKS, AKSS and WOMAC patient reported outcomes remained significantly improved in comparison to preoperatively. For those 70 years or older, 10-year survivorship was 92.4%, compared to 85.0% for those under 70 years old. CONCLUSION: Medial fixed all-polyethylene tibial bearing UKA demonstrates acceptable long-term survivorship and patient outcomes. It appears to be a suitable option for the treatment of medial compartment OA, particularly in older patients.

Minimally invasive surgery (MIS) for total knee replacement; medium term results with minimum five year follow-up.

BACKGROUND: MIS TKA has been shown to offer a reduced in-patient stay, but no clinical difference at two years. Whilst there may be a benefit from earlier discharge, we need to ensure that there are no detrimental effects in the medium and long-term following MIS-TKA. To report the mid-term result from a prospective randomised controlled trial (RCT) comparing MIS-TKA with standard approach for TKA. METHODS: Using knee score questionnaires, we collected patient reported outcome measures (PROMs) regarding pain and function. Sixty-six patients (from an eligible cohort of 83 patients) completed the mid-term postal follow-up. RESULTS: There was no significant difference between groups for change in score from pre-operative to final follow-up in all three PROMs. Mean MIS and standard group improvement was: AKSS 53 and 51 (p=0.7644), OKS 15 and 16 (p=0.2341) or WOMAC 15 and 15 (p=0.9900) respectively. Both groups showed improvement in pain and function with no significant difference between groups. There was no difference between groups for revision due to malalignment at a mean six year follow-up. CONCLUSIONS: In addition to the early benefits regarding hospital stay and complications, we have found that at a mean of six years there was no increase in malalignment, pain or function with MIS techniques.

The Journey patellofemoral joint arthroplasty: A minimum 5year follow-up study.

BACKGROUND: The Journey patellofemoral joint arthroplasty (PFA) was designed to improve patient outcomes following surgical management of patellofemoral joint osteoarthritis. It is based on the asymmetric trochlear geometry of the Genesis II total knee arthroplasty, with Oxinium components, to provide a reliable treatment option in an often young, high demand group of patients. METHODS: We report the minimum five year functional outcome and survivorship of the Journey PFA performed at our institution between October 2005 and September 2009. RESULTS: A total of 101 Journey PFAs were implanted in 83 patients, and we have complete outcomes for 90 implants (89%). There were 80 implants in female patients, and the mean age at time of surgery was 60years (26 to 86). The median Oxford Knee Score (0 to 48) improved from 18 to 30, and median Western Ontario and McMaster University Osteoarthritis Short Form Index (0 to 60) improved from 22 to 35. There were a total of 12 revisions, with mean time to revision 50months (10 to 99). CONCLUSIONS: The Journey PFA gives a good medium-term functional outcome with 88% survivorship at a mean of seven years. This is the largest study of Journey PFA in the literature, and it provides a reliable option for patients with isolated patellofemoral joint osteoarthritis when arthroplasty is considered.

Kneeling requirements and arthroplasty surgery.

We investigated the physical characteristics and symptoms related to kneeling in a normal population. One hundred people were recruited at random. Of these, 27 subjects had knee pain and 73 were normal. Measurements were in kilograms with subjects on scales in three positions: standing, kneeling at 90 degrees and kneeling at full flexion. All 73 normal subjects could kneel at 90 degrees with an average of 94% of their body weight and at full flexion with an average of 51% of their body weight. The 27 subjects with knee pain were able to kneel at 90 degrees with an average of 97% of their body weight and in full flexion with an average of 50% of their body weight. Weight transmitted through the knees at full flexion is significantly less than when at 90 degrees whether subjects had pain or not. Future development of knee arthroplasty, when catering for kneeling might need to concentrate on achieving a better range of movement.

Minimally invasive total knee arthroplasty; a pragmatic randomised controlled trial reporting outcomes up to 2 year follow up.

BACKGROUND: We present a prospective, randomised, multi-surgeon, controlled trial comparing minimally invasive (MIS) and standard approach total knee arthroplasty (TKA). METHODS: Participants underwent unilateral TKA. Patients were randomised to Bristol, quadriceps sparing MIS or standard medial parapatellar approaches. Length of stay with secondary outcome measures including knee range of movement, Oxford Knee Score (OKS), Western Ontario and McMaster Universities Arthritis Index (WOMAC) and American Knee Society Score (KSS) up to 2 years. Radiographic and post operative assessment was blinded. RESULTS: 86 patients (92 knees) participated in the study. Mean operative time between MIS and control groups was 95.5 (95% CI 90.0-101.0) and 94.8 (95% CI 88.2-101.4) minutes respectively. Mean readiness for discharge was shorter in the MIS group 4.5±1.5 (95% CI, 4.1-4.9) days versus 5.9±2.7 (95% CI, 5.1-6.7) days amongst controls (p=0.004). Patients in the MIS group had fewer complications (p=0.003). One patient developed a deep vein thrombosis (DVT) and one required revision surgery, both in the control group. 83 patients completed follow up to 2 years (40 MIS, 43 controls). Range of movement and other outcome measures improved up to 1 year post-operatively with no statistically significant differences between MIS and controls. We found no evidence of radiographic loosening in either group at the 2 year follow up. CONCLUSIONS: MIS offers reduced length of stay and fewer complications for patients following TKR without evidence of component mal-alignment. Our findings of fewer systemic complications in MIS TKR patients warrant further future study. LEVEL OF EVIDENCE: Level 1.

BASK presentations: progress to journal publication.

Scientific conferences, such as the British Association for Surgery of the Knee (BASK) annual meeting, provide an important channel for the exchange of information between researchers. However, the ultimate means of disseminating research information is publication in a relevant peer-reviewed journal. The goal of this study was to follow up published abstracts in the Journal of Bone and Joint Surgery, British Volume supplement from the annual BASK conference and determine how many presented abstracts progressed to article publication in a peer-reviewed journal. Combined Google Scholar and PubMed searches of 602 BASK abstract titles over a 10-year period were performed, and the resulting articles were reviewed to confirm that they were directly associated with the corresponding abstracts. Two hundred (33.2%) abstracts presented at BASK conferences over a 10-year period were found in online or print format. This amount is comparable with other similar conferences' publication rates. Only one-third of abstracts presented at the BASK conference were converted to journal publication as full articles. This may be due to multiple rejections, lack of time, relocation of the authors, or a reluctance to publish negative findings. Alternatively, changes in an abstract's title for publication prevents online search engines from identifying the final article and may explain some disparity. Furthermore, presented abstracts may not survive the strict peer-review process required for journal publication. Because these findings from BASK mirror other specialty meetings, clinicians should accept the results of orthopedic meeting proceedings with some level of caution.

The Posterior Condylar Offset Ratio.

INTRODUCTION: Posterior Condylar Offset is an area of interest in knee arthroplasty research and clinical outcome. The aim of the study is to define a quantifiable Posterior Condylar Offset Ratio, a normal value for this ratio and to confirm its reproducibility on pre-operative radiographs. METHOD: We propose a new Posterior Condylar Offset Ratio which is defined as the maximal thickness of the posterior condyle projecting posteriorly to a straight line drawn as the extension of the posterior femoral shaft cortex, divided by the maximal thickness of the posterior condyle projecting posterior to a straight line drawn as the extension of the anterior femoral shaft cortex on a true lateral radiograph of the distal quarter of the femur. We have measured this on 100 true lateral radiographs (50 females, 50 males, and mean age 65 years). RESULTS: The mean ratio was 0.44 (SD 0.02) and was shown to have good reproducibility (intra-observer error 0.899 and inter-observer error 0.882. The ratio was also very consistent between male and female patients (0.44 (SD 0.02) for the males and 0.45 (SD 0.02) for the females). Adjusting the ratio for reported posterior condyle articular cartilage thickness increased the ratio to 0.47 (SD 0.02). CONCLUSION: We suggest our Posterior Condylar Offset Ratio is a useful tool to aid further research in this area of knee arthroplasty and propose a normal value of 0.44 on radiographs and 0.47 on post-operative knee arthroplasty radiographs.